Impact Loads on Tension Composite Multi-Strings of Insulator After a Single String Breaks

The dynamic impact load after a single insulator of a tension composite multi-strings of insulator (MSI) set has failed is a key factor that should be considered in design. In this paper, an experimental method to obtain the dynamic tensile impact factor (DTIF) is established by considering a typical double-strings set, which is commonly used in practical engineering. A nonlinear numerical simulation method based on the finite element model, which is convenient for cases that are more complex than the double-strings set, is proposed to calculate the DTIF and demonstrated through the experimental results. The values of the DTIF on the unbroken insulator string obtained by the experimental models fall between 2.6 and 3.3, which should be a very valuable reference for the design of composite MSI sets. The size of connection fittings is a key factor that influences the DTIF, and the yoke height between the insulator strings and the conductors is the most sensitive parameter. The application of the proposed method to calculate the DTIF can improve the existing design approach to ensure the safety of the tension composite MSI sets, especially for high voltage transmission lines.